Connection for blasting fuses and method of using the same



y 1934. L. CZR. MALLET 1,968,565

CONNECTION FOR BLASTING FUSES AND METHOD OF USING THE SAME 7 Filed March 14, 1930 INVENT'OK l [.K. m; W humi ATTORNEYS.

' and in winding the Patented duty 31, i93

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The use of detonating fuses has been considerably developed during the last few years, particularly in the exploitation of quarries by blasting in large quantities or of open well mines by large steps, as also for the simultaneous blasting of central holes, called plug for advancing galleries cut out in the rock.

The only type of fuse which is in general use today is composed of a core of trinitrotoluene or TN. '1. covered with a casing of lead. It has, in effect, complete safety because of its resistance to damp and its lack of sensitiveness to shocks'.

This last quality which is caused by the small sensitiveness of T. N. T. to the various agents capable of causing detonation, entails, however, the inconvenience of making it very difiicult to connect the main fuse to one or more secondary fuses.

The method usually employed in practice for connecting two fuses, and more particularly two fuses running in approximately perpendicular direction and known under the name of split connection, consists in splitting the secondary fuse longitudinally over a length of 12 to 15 cm. two halves of the split fuse in opposite directions round the main fuse. This method has the disadvantage of requiring a special tool for carrying it out and of causing the loss of a length of fuse equal to that which has been split. Finally, this type of connection is liable to come unfastened and above all it is very dimcult to make it prood against dampness.

It would be easy to obviate these dimculties by placing at the end of each secondary fuse a detonator placed in contact with the main fuse, and fixed there, but then the principal cause of safety in the use of T. N. T. fuses would be lost, namely, that of firing any number of holes using a single detonator of Cordeau containing, for instance, fulminate of mercury or lead azide i. e., sensitive to external shocks, this detonator of Cordeau being placed at the last moment at one end of the main fuse while all the other connections are prepared in advance.

The present invention consists in fixing at the end of each secondary fuse of Cordeau and connecting to the main fuse a container of suitable form, for example in the form of a tube closed at one end containing an explosive of intermediate sensitiveness between the T. N. T. constitutin'g cury, lead azide, etc.). This explosive may be for example, melinite (picric acid) tetryl (tetraholes, at one shot the core of the fuse and the firing charges contained in the detonators (fulminate of mer-' March 14, 19%, Seriai No. 435,685

France March 23, N29

nitro-methyl-aniline) or any other explosive having the same order of sensitiveness.

This sensitiveness must be small enough to avoid the risk of the explosive protected by the walls of the container holding it from exploding under the action of an external shock, as for example, the fall of a stone or tool. It must be great enough for the explosive in question to be fired by contact at asingle point between the walls of the container and a'detonating fuse or of another similar container fired itself by external action.

The invention may be carried out by placing the explosive charge of intermediate sensitiveness at the bottom of a metallic'tube closed at one end and of dimensions similar to those of the external covering of detonators used in mining work. This tube, the internal diameter of which is equal to the external diameter of the fuse, constitutes the connector proper and forms a. part of the present invention as a new industrial product. I

The secondary fuse of Cordeau is inserted in the free space remaining above the charge in the tube and is held in place by crimping. Each con- 3g nector is united to the main fuse by any appropriate means, for example, by placing the connector across the main fuse or on another connector and holding it on the said fuse by a tie or adapter, which may be a rubber ring, an elastic metallic clasp or any other similar device.

To prevent the connector slipping over the main fuse when it is placed across the latter, it is advantageous to provide a connector near its bottom with two collars projecting outwards or W to flatten the tube so as to form on one face or on two opposite faces a kind of transverse groove in which the main fuse will fit.

In the work of advancing galleries, when it is the question of firing any number of fuses togather for firing charges placed at small distances apart, it is sufficient to cap each fuse with a connector, to unite all the connectors in a bundle by means of a tie made, for example, by means of two elastic rings, and to place in the m0 centre of this bundle an ordinary detonator, the explosion of which is caused by a fuse or an electric primer.

The type of connector forming the subject of the present invention has the great advantagema of being easily made absolutely damp proof. It is suflicient to place on the connector at the point where the fuse enters it a piece of rubber tubing which, once the secondary fuse is in place, is stretched over the mouth of the connector and over a certain length of the secondary fuse gripping both of them without leaving any space for water to enter; with rubber of a good quality such a joint will withstand indefinitely a pressure of several metres of water.

This rubber tube may be supplied rolled on the mouth of the connector 50 that by unrolling it after having threaded the fuse into the connector the tube covers the fuse.

In the accompanying drawing are shown by way of example several ways of making the connector which is the subject of the invention.

Figure 1 is a diametrical section of the connector.

Figure 2 is a side view of the connector fixed on a main fuse. v

Figure 3 is a plan view of Figure 2.

Figure 4 is a perspective view of a metallic clasp.

Figure 5 is a view similar to Figure 2 showing how the metallic clasp of Figure 4 is put into place.

Figure 6 is a front view of a different type of connector. I

Figure '7 is a side view, the connector being fixed to the mainfuse.

Figure 8 is another modification similar to Figure 7. v

Figure 9 shows a rubber and the secondary fuse.

As shown in Figure 1, the connector is made up of a tube 1 provided with two circular collars 2 and 3, into which a charge 4 of explosive of intermediate sensitiveness has been introduced, for

joint for the connector example, tetryl. The secondary fuse 5 is introduced into the tube 1, pushed into contact with the charge 4, and is then crimped at 6 in the known way. Referring to Figures 2 and 3, the connector 1 is shown placed against the main fuse 7 perpendicular to the axis of the latter so as to put the connector and fuse into contact at the point 8. A rubber ring 9 passes round first the connector 1, then the fuse '7, then again the connector 1, fixing the latter on the fuse. It is obvious from these figures, without further explanation, how the collars 2 and 3 prevent the fuse 1 from sliding on the connector 7, which they enclose.

Instead of using a rubber ring, such as that of Figures 2 and 3, use may be made, for fixing the connector to the main fuse, of a metallic clasp 10, such as that of Figure 4. This clasp is first threaded into the position 10a shown in Figure 5. The fuse '7 is placed against the connector 1, between the collars 2 and 3, then the clasp is swung round into the final position 1022, shown in dot and dash lines, passing through the intermediate position 100, shown in full lines, by exerting pressure in the direction of the arrow f on a projection 11 formed by bending back a part of the clasp 10.

In the variation shown in Figure 6, the connecter 1 is flattened at 12-13 in the form of. a transverse groove which may be fitted to the fuse '7.

In the variation of Figure 8, there is only a single groove 12 so as not to diminish the thickness of the explosive of intermediate sensitiveness in its contact zone with the main fuse.

In the modifications of Figures 6, "I, 8 instead of a point contact 8 between the fuse and the connector there is a line or surface contact.

In Fig. 9 I have shown a piece of rubber tubing 14 rolled back on itself around the connector 1, so that a joint may be quickly and easily made by unrolling the rolled part on the fuse 5, as shown in dotted lines at 14.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed I declare that what I claim is:--

1. In a connection for a main line with branch lines of Cordeau, a container, a priming explosive in the container of intermediate sensitiveness between the explosive constituting the Cordeau and the fulminating explosives constituting the'ch-arge of the usual detonators, said container having a tubular part extending therefrom, and a fuse introduced into said part to make contact with the explosive of the container.

2. In a connection for a main line with branch lines of Cordeau, a tubular container hai ing two successive variations of curvature separated by an attaching portion, a priming explosive in the container of intermediate sensitiveness between the explosive constituting the Cordeau and the fulminating explosives constituting the charge of the usual detonators, and a main fuse lodged in said attaching portion.

3. In a connection for a main line with branch lines of Cordeau, a tubular container having two collars extended from the container and separated by an attaching portion, a primary explosive in the container of intermediate sensitiveness between the explosive constituting the Cordeau and .the fulminating explosives constituting the charge of the usual detonators, and a main fuse lodged in said attaching portion.

4. In a connection for a main line with branch lines of Cordeau, a tubular containerhaving' two local depressions of the wall and having an attaching portion therebetween, a priming explosive in the container of intermediate sensitiveness between the explosive constituting the Cordeau and the fulminating explosives constituting the charge of the usual detonators, and a main fuse lodged in said attaching portion.

5. In a connector for fuses of relatively low sensitiveness as compared to usual detonators sensitive to external shock, a container, a priming explosive in the container of intermediate sensitiveness and insensitive to external shock, said container being formed tending from the container and with an attaching portion, a secondary or detonating fuse introduced into said part to make contact with the explosive of the container, a main fuse lodged in said attaching portion and attachment means for securing contact between said main fuse and the connector.

6. In a connection for a main line with branch lines of Cordeau, a tubular container formed with an external attaching portion, a primingexplo sive in the container of intermediate sensitiveness between the explosive constituting the fuse and the fulminating explosive constituting the charge of Cordeau and insensitive to external shock, a tubular part extending from the container, a fuse introduced into said part to make contact with the explosive of the container, a main fuse lodged in said external attaching portion, and an elastic tie passing over the connector and over the main fuse for retaining the connector and main fuse in intimate contact.

7. In a connection for a main line with branch with a tubular part ex- 0 lines of Cordeau, a container formed with an ex-' Cordeau and insensitive to external shock, a tubu- I lines of Cordeau, of a lar part extending from the container, a fuse introduced into .said part to make contact with the explosive of the container, a main fuse secured to the exterior of said connector, and a flexible metallic wire bent four times upon itself defining four planes parallel in pairs main fuse to the connector.

9. In a connection for a main line with branch lines of Cordeau, a container, a priming explosive in the container of intermediate sensitiveness be tween the explosive constituting the charge of Cordeau and insensitive to external shock, a tubular part extending from the container, a fuse introduced into said part to make contact with the explosive of the container, and a main fuse crossing said connector, said connector having an external projection and attaching portion constituted by a supplementary local bending formed on said container for receiving and holding said fuse.

10. In a connection for a main line with branch lines of Cordeau, a tubular container having two successive variations of curvature separated by an attaching portion, a priming explosive in the container of intermediate sensitiveness between the explosive constituting the fuse and the fulminating explosives constituting the charge of Cordeau, a main fuse lodged in the said attaching portion, a flexible rubber tubing formed on said container and rolled back on itself so that a joint may be quickly and easily made by unrolling the rolled part of the tubing on the fuse lodged therein.

11. In a connection for a main line with branch connector therefor providing a container for intimate-exterior contact with for securing said a tubular shell having one of said fuses and receiving the other said fuse within the container,- an explosive within the container of intermediate sensitiveness between that of the fuse and an explosive constituting the charge of Cordeau, said intermediate explosive in said container comprising melinite.

12. In a connection for a main line with branch lines of Cordeau, of a connector therefor providing a container for intimate exterior contact with one of said fuses and receiving the other said fuse within the container, an explosive within the container of intermediate sensitiveness between that of the fuse and an explosive constituting the charge of Cordeau, said intermediate explosive in said container comprising tetryl.

13 A fuse connection comprising in combination a main line and a branch line of Cordeau, a tubular shell adapted to fit over and engage the free end of the branch line, a bead on said shell and means for engaging the bead and securing the tubular shell to the main line.

14. A fuse connection comprising in combination a main line and a branch line of Cordeau, a tubular shell adapted to fit over and engage the free end of the branch line, a bead on the shell, and clamping means adapted to engage the bead and the main line for securing them in close contact.

15. The invention of claim 13 in which a detonating charge is incorporated in the tubular shell.

16. A fuse connection comprising. in combination a. main line and a branch line of Cordeau, incorporated therein a booster charge, and adapted to fit over and engage the free end of the branch line, a bead on said shell and means engaging the bead and the main line. a 1

17. A fuse comprising in combination a main line and a branch line of Cordeau, a tubular shell adapted to fit over and engage the free end of the branch line and having a detonating charge incorporated therein in contact with the end of the Cordeau fuse, a bead on the shell, and means adapted to engage the bead and the main line for securing them in close contact.

LOUIS CHARLES RICHARD MALLET. 

